#include <QCoreApplication>
#include <iostream>
#include <math.h>
using namespace std;
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    const double Pi=3.14;
    int A;
    double r=0,d=0,l=0,s=0;
    cout<<"Vvedite nomer elementa u znachenie(Radius-1,Diametr-2,Dlina-3,Ploshad kruga-4: ";
    cin>>A;
    switch (A)
    {
    case 1:cin>>r;
                break;
    case 2:cin>>d;r=0.5*d;
                break;
    case 3:cin>>l;r=l/(2*Pi);
                break;
    case 4:cin>>s;r=sqrt(s/Pi);
                break;
    default:
        cout<<"Nevern vvod";
        break;
    }
    d=2*r;l=2*Pi*r;s=Pi*r*r;
    cout<<"Radius: "<<r<<endl<<"Diametr: "<<d<<endl<<"Dlina: "<<l<<endl<<"Ploshad: "<<s;
    return a.exec();
}
